<template>
  <div class="pagination">
    <button 
    :disabled="pageNo ===1"
    @click="$emit('newPageNo',pageNo-1)"
    >上一页</button>
    <button 
    v-show ="startEndPage.start>1"
    @click="$emit('newPageNo',1)"
    >1</button>

    <button v-show ="startEndPage.start>2">···</button>

    <button 
    v-for="page  in startEndArr" 
    :key="page"
    :class="{active:pageNo===page}"
    @click="$emit('newPageNo',page)"
    >{{page}}</button>


    <button v-show="startEndPage.end<totalPages -1">···</button>
    <button 
    v-show="startEndPage.end<totalPages"
    @click="$emit('newPageNo',totalPages)"
    >{{totalPages}}</button>
    <button 
    :disabled="pageNo ===totalPages"
    @click="$emit('newPageNo',pageNo+1)"
    >下一页</button>

    <button style="margin-left: 30px">共{{total}} 条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  //收到当前页数-----总页数-----连续页码数字
  props:["pageNo","totalPages","continuePage","total"],
  computed:{
    startEndArr(){
        const arr=[]
        for (let i= 1; i <= this.startEndPage.end; i++) {
            if(i>=this.startEndPage.start){
                arr.push(i)
            }
        }
        return arr
    },
    startEndPage(){
        const {pageNo,totalPages,continuePage} = this
        let start = 0 ,end = 0
        //判断当连续页大于总页数的时候
        if( continuePage>totalPages){
            start = 1,
            end = totalPages
        }else{
            //如果总页数大于连续的时候
            start = pageNo -Math.floor(continuePage/2)
            end = pageNo +Math.floor(continuePage/2)

            //如果start小于1了
            if(start<1){
                start =1,
                end = continuePage
            }
            //如果end大于总页数了
            if(end>totalPages){
                end = totalPages
                start = totalPages - continuePage +1
            }
        }

        return {start,end}
    }
  },
};
</script>

<style lang="less" scoped>
.pagination {
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>